Mechanism for adjusting the length of stitch on a sewing machine



Feb. 27, 1962 M. FRESARD 3,022,756 MECHANISM FOR ADJUSTING THE LENGTH OF STITCH ON A SEWING MACHINE Filed Jan. 26, 1960 avg/4W zerland Filed Jan. 26, 1960, Ser. No. 4,671 Claims priority, application Switzerland Jan. 30, 1959 SClaims. (Cl. 112-210) The present invention has for its subject a mechanism for adjusting the length of stitch on a sewing machine, comprising a control shaft of which the angular movements in one direction or the other from a median position, control the forward or return movements of the feeder.

It has been known for a long time, in connection with sewing machines, to provide a handle or a control lever for adjusting the length of stitch, permitting of adjusting said length either for an advance movement, or for a return movement of the feeder.

Other machines are known in which the mechanism for adjusting the length of the stitch comprises a manual control member capable of being constituted by a control.

wheel or a lever permitting of the adjustment of the length of the stitch for a single advance movement. In these machines, the return movement of the feeder is controlled by a second operating member, for example a lever or a push-button, which the user of the machine can move against the action of a spring, for provoking a momentary return movement of the feeder. These machines have the inconvenience of rendering impossible the operation on the rearward movement of the feeder when the user of the machine has to hold the parts to be sewn with two hands. for its object to remedy this disadvantage by permitting of a machine of the last type mentioned above, to function on rearward movement, without it being necessary to exert a pressure continuously with the hand on the second operating member of the control mechanism for adjusting the length of the stitch.

The mechanism for adjusting the length of the stitch according to the invention is characterised by the fact that it comprises a first lever secured to said control shaft and of which one end constitutes a handle, while the other end of said lever is provided with a slide in which is hinged one end of an intermediate lever, oscillating relative to the framework of the sewing machine, and the other end of said lever carries a feeler finger. A cam of double profile is provided in a control wheel for adjusting the length of the stitch, the whole arrangement being so located that the profiles of the cam constitute a stop for the feeler finge and thus for the control shaft returned by a spring in the direction of maximum advance of the feeder. The handle formed by the first lever, permits imparting a momentary return movement to the feeder, which movement is capable of being controlled, on the other hand, by adjustment of the control wheel.

One form of construction of the mechanism according to the invention is shown diagrammatically and by way of example in the accompanying drawings, wherein:

FIG. 1 is a view in plan of this mechanism, while FIG. 2 is a View in section on the line II-II of FIG. 1.

This mechanism for adjusting the length of the stitch described with reference to the drawing, is supposedly mounted on a sewing machine, in the framework 1 of which is disposed a vertical shaft 2, constituting the control shaft of which the angular displacement in one direction or the other, from a medial position, controls the advance or return movements of the feeder of the machine. A feeder of the type herein referred to is illustrated and The mechanism according to the invention hasite St-te s Patent described in US. Patent No. 2,647,481. On the upper end 3 of said control shaft 2 is secured a first lever 4, of which one end 5 constitutes a handle, while the other end 6 has a slide 7. In fact, as shown in FIG. 1, said slide 7 is formed by a fork, between the prongs 8 of which engages a trunnion 9 depending from one end of an intermediate lever 10. This intermediate lever 1t) is thus hinged in the slide 7 by its trunnion 9. Said lever it) is mounted for oscillation on a spindle 11 secured rigidly t0 the framework 1 of the machine and said spindle passes through an elongated opening 28 of the lever 4. The other end of said intermediate lever 13 carries an upstanding feeler finger or stud 12.

Above the levers 4 and 10, a control wheel 14 is socured, by means of a spindle 13, to the framework 1 of the machine. In this wheel 14- is drilled a cam 15 of double profile. The feeler finger 12 is thus engaged in the cam 15 and normally bears against the internal profile 16 of the cam 15. In fact, a spring, not shown, tends to cause the control shaft 2 to turn in the direction of the arrow 17 in FIG. 2, that is .to say in a clockwise direction relatively to FIG. 1. As a result, the intermediate lever 10 also tends to rotate in a clockwise direction, whereby the feeler finger 12 is displaced in the direction of the internal profile 16 of the cam 15. This profile 16 thus constitutes a stop for the feeler finger 12 and thus for the control shaft 2 returned by its spring in the maximum advance direction of the feeder. This profile 16 is formed in such a manner that when driving the control wheel 14 in a clockwise direction relatively to FIG. 1, from the zero position, there is provoked an elongation of the length of the stitch.

This control wheel 14 is maintained in a stable manner in any one of its angular positions, by reason of a plunger piston 18 sliding in a bore 19 of the framework of the machine, under the action of a spring Zil. The end 21 of said piston 18 is sharpened in such a manne as to engage fine teeth 22 provided at the periphery of the control wheel 14. On the upper face 23 of said control wheel 14 is indicated a scale 24 permitting of reading opposite a mark carried by the framework 1 of the machine the value of the length of the selected stitch.

To permit of the adjustment for setting the control wheel 14 at zero, the trunnion 9 is secured to the lever ill by an eccentric device 25 capable of being locked in the position into which it has been moved by means of a screw 26 engaging transversely in the lever 10 and of which the point serves to lock the eccentric device 25. The second profile 27 of the cam 15, that is to say the external profile of said cam, is provided in such a manner as to impart to the feeder of the sewing machine, when the feeler finger 12 applies thereto, under the action of a pressure applied to the handle 5, a recoil movement of the same amplitude as that imparted by the first profile 16 for the advance movement, for the same position of the adjusting wheel 14.

The utilisation of the mechanism for adjusting the length of the stitch above described with reference to the accompanying drawing is effected in the following manner:

When the user of the machine desires to make a sewing of a determined length of stitch, for example that corresponding to the figure 2 of the graduation at the end of this, she may desire to stop this sewing by effecting some sewing stitches by rearward movement, This operation is effected by moving the handle 5 towards the right with reference to FIG. 1, against the action of the return spring of the shaft 2, until the feeler finger 12 comes to bear against the second profile 27 of the cam 15. In this position of thefeeler finger 1,2, the.

shaft 2 controls a recoil movement of the feeder of an amplitude equal to that determined by the numeral 2 of the graduation 24 which was selected initially. When the user of the machine releases the handle 5, the return spring of the shaft 2 provokes the return of the feeler finger 12 against the profile 16 of the cam 15, that is to say that the sewing machine resumes its initial adjustment of the length of the stitch corresponding. to the numeral 2. v I

During particular sewing operations, during the course of which the user of the machine must hold the parts to be sewn with both hands, the sewing stitches during the rearward movement may be stitched without it being necessary to hold the handle 5 constantly. In fact, in this case, it is sufficient to adjust the wheel 14 in such a manner that the graduation figures 24 corresponding to rearward movement of the feeder are brought opposite the mark indicated on the framework 1 of the machine. In this case, the feeler finger 12 is located in the confined zone of the profiles 16 and 27 of the cam 15, a zone constituting, to some extent, a compuls sory cam. For this reason, the handle 5, carried by the lever 14, is inoperative. It will beunderstood thatwh eni the user desires to effect a fresh normal sewing, it isnecessary to move the wheel 14 for bringing the signs of the graduation 24 corresponding to the movement of normal advance of the feeder opposite the mark indicated on the framework 1.

Numerous modifications of construction of said mechanism for adjusting the length of a stitch may be imagined. Thus, the control wheel 14 may be replaced by a control lever. As regards the general disposition of the wheel 14 and of the levers 4 and 10 about vertical spindles 2, 11 and 13, this may be different, according to the types of sewing machines to which this adjusting mechanism may be applied. Thus it is possible to very readily imagine such an adjusting mechanism in which the spindles 2, 11 and 13 are disposed horizontally.

Preferably and for facilitating the adjustment of the lengths of stitch of small amplitude, the adjusting ranges decrease from 0 to 4 on the scale 24, that is tosay that the profiles 16 and 27 are of such a shape that they permit of a better fineness of adjustment by means of the control wheel 14 for lengths of stitch of small amplitude than for those of large amplitude,

I claim: 7

1. A sewing machine having a frame, a control shaft within said frame and adapted to be connected to a feeder, spring means connected to said control shaft and,

feeder while maintaining a constant stitch length, one end.

of said lever serving as a handle, a slide at the other end of said lever, a second lever disposed above said first lever, mounting means for said second lever, said mounting means secured to said frame to permit oscillating move-' ment of said second lever relative thereto, means at one end of said second lever connecting the same to said slide of the first lever, an upwardly projecting stud at the opposite end of said second lever, 21 control wheel for determining adjustment of stitch length in both a forward and reverse movement connected to said frame and disposed above said second lever, the bottom surface of said wheel having an arcuate shaped aperture therein, the opposite edges of said aperture forming a cam having an inner and outer profile and receiving the stud on said second lever, said stud normally maintained in contact with the inner profile by the action of said spring means on the control shaft, movement of said stud away from said inner profile and against said outer profile by manipulation of said first lever in a counterclockwise direction causing the momentary reversal of the direction of travel of said feeder, and release of said first lever causing return of said stud to engagement with said inner profile of the cam and resumption of initial adjustment of stitch length.

2. A mechanism according to claim 1, wherein said slide comprises a bifurcated member and the means atv one end of said second lever connecting the latter to said first lever comprises a trunnionconfined between the arms of said slide.

3. A mechanism according to claim 2, wherein said trunnion is securedto said second lever by an eccentric mem e P m n an. iv tnem a d on w e l;

3 passes through the elongated opening in said first lever,

5. A mechanism for adjusting the stitch length and feed direction of the feeder of a sewing machine comprising a cam having an arcuate shaped aperture therein, a shaft around which said cam rotates, the opposite edges of said aperture forming inner and outer control profiles in the general shape of a spiral winding in inverse directions with regard to a median line concentric to said shaft from the point of zero amplitude to the point of maximum amplitude of the stitch length, a control wheel in which said cam is mounted for determining the adjustment of the stitch length, a first lever for permitting momentaryreversal of the direction of said feeder while maintaining a constant stitch length, a second lever mounted above said first lever and beneath said controlwheel, a stud on said second lever and engageable with said cam, said stud movable from one to theother of said cam profiles whereby the inner profile of said cam which provides the stitch length for forward movement is extended beyond the zero amplitude point to permit adjustment of the stitch length in a continuous manner by movement of saidcam through operation of said control wheel from the maximum reverse amplitude to the maximurnforward amplitude,

References Cited in the file of this patent UNITED STATES PATENTS F ance 19 7 

